The present invention relates generally to an improved core plug for protecting the ends of hollow paper cores on which paper, plastic, fabric and other materials are wound for storage, shipment and use. More particularly, the present invention relates to a core plug formed from wood, plastic, or a composite woody material, that has increased strength over existing core plugs as a result of the development of a novel means for removing the core plugs from cores after use.
In paper mills, textile mills and the like, rolls of paper and/or fabric are generally wound on tubular cores which are usually made of a paper material such as cardboard or paperboard. These cores are relatively strong except that they are vulnerable at their ends where they can be easily damaged. During shipment and handling, the rolls of paper and other materials are repeatedly picked up and moved, and if the core ends become deformed in any way, the entire roll of paper or other material becomes unusable because it cannot be properly chucked. Thus, in order to protect such cores, core plugs are commonly inserted into the ends of the core.
Core plugs are presently available in a number of sizes to accomodate different sized cores. Such core plugs are formed from a variety of different types of materials, and include various distinctive features to increase their strength and utility. However, in general, the majority of such core plugs are formed from wood or molded wood material. Molded wood core plugs are available from Moldwood Corporation, Drawer 430, York, Ala. 36925. Core plugs supplied by Moldwood Corporation and as described in their sales literature are conventional in design with a centrally located hole for removing the core plugs from cores. Most core plugs must be removed before the rolls of paper, fabric or the like can be used. The core plugs may be removed by inserting a metal bar or rod into the hole provided in the plug where the plugs are wedged or pulled out. However, in general the metal bar or rod is inserted in the hole in one core plug and butted against the inside of the opposite core plug so that it can be driven out. Since core plugs may differ in size, the holes provided therein may also be of different size. Generally the bars or rods that are used to remove the core plugs are metal stock of from about 1/2 to 3/4 inch in diameter. Thus the holes in the core plugs must be at least as large as the bars or rods used to remove them.
Other core plug designs are disclosed in U.S. Pat. No. 4,015,711; U.S. Pat. No. 3,627,220; U.S. Pat. No. 3,547,367; U.S. Pat. No. 2,196,378; and, U.S. Pat. No. 1,919,769. The core plugs described in the aforementioned patents are in the form of shells made from plastic materials or metal, and with the exception of the core plug disclosed in U.S. Pat. No. 2,196,378, all include a centrally located hole for removing the core plugs from a core. In U.S. Pat. No. 2,196,378, the core plug includes a pair of intersecting ribs which divide the face of the core plug into four quadrants. Thus, in order not to inhibit the increased strength provided by the intersecting ribs, the hole for removing the core plug is located off center in one of the quadrants.
Notwithstanding the features and advantages described for the core plugs presently in use, the core plug of the present invention offers increased strength and durability over existing core plugs.